Appliance for Water-Jet Surgery

ABSTRACT

An appliance for water-jet surgery is provided that includes a plurality of supply cylinder and piston arrangements in each of which is stored a working fluid that can be expelled, by means of the piston, through an outlet into a pressure conduit. At least one actuation device is provided to actuate the piston of each supply cylinder. By means of a change-over device to change the actuation from the piston of one supply cylinder to the piston of another supply cylinder, it is ensured that the working fluid can be expelled into the pressure conduit from consecutively emptying supply cylinders. As a result, an apparatus with a small structure that is achieved by simple means is disclosed.

The invention relates to an appliance for water-jet surgery, in which afluid is expelled from a nozzle under high pressure for the selectivecutting of tissue.

Customarily in the case of such an appliance a supply cylinder having an(initially closed) outlet at one end is filled with a working fluid,such as Ringer solution, and at its other end is closed by means of apiston. This supply cylinder is then inserted into a stably positionedchamber in an appliance housing. After closure of the housing anactuating rod driven by a hydraulic cylinder is placed in contact withthe piston in the supply cylinder. Now the known appliance is ready foroperation. During operation the pressure that must be applied to thefluid is generated by the hydraulic cylinder.

So that during an operation a sufficient amount of working fluid isavailable with no need to exchange the supply cylinder, a procedure thatwould involve a not inconsiderable interruption of the operation, thesupply cylinder must have a relatively large volume. The larger thecylinder bore is made, the larger must be the force exerted by thehydraulic system, and hence a correspondingly greater stability isrequired of the receptacle for the supply cylinder. On the other hand,if the volume of the supply cylinder is increased by lengthening it, andhence lengthening the stroke of the piston, the result is an increase inthe overall height of the appliance. The present-day compromise hasproduced supply cylinders with a diameter of ca. 60 mm, with the resultthat the associated appliances are constructed as stands and have aheight of ca. 1,200 to 1,500 mm. The necessary actuation devices, i.e.the hydraulic cylinder along with the associated hydraulic pump, areextremely elaborate and very awkward to use.

Furthermore, in the case of “small” operations for which only a slightamount of fluid is used, the excess working fluid must be discardedbecause of the sterility requirements for a working fluid, whichincreases the operating costs of the known appliance.

It is the objective of the invention to disclose a simple appliance thatenables economical operation while reducing the structural complexity.

This objective is achieved in the case of an appliance for water-jetsurgery by providing a plurality of supply cylinders, in which a workingfluid is stored and from which the fluid can be expelled through anoutlet into a pressure conduit, by means of a piston. At least oneactuation device is provided to actuate the pistons. In addition, achange-over device is provided by means of which the actuation isshifted from the piston of one supply cylinder to the piston of anothersupply cylinder, so that the working fluid can be expelled into thepressure conduit from the supply cylinders one after another, as theyare consecutively emptied.

Thus an essential point of the invention resides in the fact that theone (single) supply cylinder previously provided is here subdivided intoa plurality of correspondingly smaller supply cylinders. This measuresolves several problems simultaneously. First, because of their reduceddiameter the smaller supply cylinders can can be made of a weakermaterial, which nevertheless can resist the prevailing (very high)pressures. Second, the necessary working pressure can be produced withless force, so that the necessary actuation devices can be more simplyconstructed. Third, the appliance can be made very much smaller (e.g.,can be set onto a table), on account of the smaller stroke of thepistons. And fourth, during a “relatively small” operation fewer supplycylinders are used up than in a “larger” operation; in the presentappliance, the supply cylinders that have not been used are availablefor a subsequent operation, as their sterility is still ensured.

Preferably the change-over device is so constructed that there is someoverlap between the consecutive periods during which pistons areactuated, so that the expulsion of fluid into the pressure conduitproduced by their actuation is uninterrupted. Whereas on one hand, inthe case of the conventional large-volume supply cylinders, such anuninterrupted supply of working fluid is ensured by the large fluidvolume, with the present invention this uninterrupted supply of fluid isvery efficiently achieved.

Preferably sealing devices are provided to make the fluid outlet on thesupply cylinder water-tight, so that no manual coupling is needed for afirm connection; instead, a forceful automatic/mechanical coupling ofthe supply cylinder to the sealing device suffices.

An overlapping actuation of the pistons is especially simple when aplurality of actuation devices is provided. Then there is no need tomove the actuation devices from one piston to the next; when the numberof actuation devices corresponds to the number of supply cylinders inthe device, a simple (electronic) control means can implement thechange-over. However, it is also possible to work with a smaller numberof actuation devices (only one, in the minimal case) if the change-overdevice ensures that the actuation device is always guided to the next ina sequence of new supply cylinders.

The pistons are preferably provided with back-flow barriers, such thatafter working fluid has been ejected by a piston, the piston cannot bepushed back into a previous position from the position it has reached,in particular from its final position after all the working fluid hasbeen ejected. By this means it can be ensured that refilling isprevented and hence the possibility of working with unsterile medium canbe reliably eliminated.

At the outlet of the supply cylinder an irreversibly openable transportgasket is preferably provided. This measure likewise makes it possiblefor the use of unsterile medium to be prevented. Furthermore, such anirreversibly openable transport gasket can be very simply constructedand designed in such a way that it opens automatically when a supplycylinder is put into place or when it is first actuated. Because of thevery high pressures employed here, it is possible also to construct thetransport gasket so that it opens automatically when pressure is firstapplied.

Preferably a change-over magazine is provided, which accommodates agroup of supply cylinders. This makes handling of the apparatusparticularly simple, both during the insertion of multiple supplycylinders into the appliance and when individual actuation devices arebeing changed over from one supply cylinder to another. The change-overmagazine preferably comprises chambers that closely surround the supplycylinders. In this case the supply cylinders can be constructed with anespecially thin wall, which expands somewhat as the pressure builds upand then becomes apposed to the walls of the change-over magazine. Thereceptacle can also be made with sufficient shape stability to withstandthe pressure without becoming form-fitted to the housing.

In the change-over magazine collection devices are preferably provided,to guide the working fluid from several supply cylinders to the pressureconduit. This is especially advantageous when the working fluid is beingconducted in an overlapping manner from various supply cylinders.

Preferably ventilation devices are provided, in particular to remove airsimultaneously from conduit sections between the outlets of the supplycylinders and the pressure conduit, so that there is no interruption orpulsation of the working fluid associated with the release of airremnants. Preferably the ventilation devices are disposed in thechange-over magazine.

In one embodiment of the invention the change-over magazine is fixedlyconnected to the pressure conduit and is intended to be used only once.In this case the change-over magazine can already be filled with supplycylinders by the manufacturer, so that although the advantage of savingworking liquid (as well as the supply cylinders) is no longer obtained,all the other advantages cited above are nevertheless preserved. Aspecial advantage in this case is the ease of manipulation, inparticular with regard to sterility criteria.

Preferred embodiments of the invention will be apparent from thesubordinate claims and the following exemplary embodiments, which areexplained in greater detail with reference to drawings, wherein

FIG. 1 is a schematic sectional drawing of a first embodiment of theinvention with inserted magazine, prior to actuation,

FIG. 2 shows the arrangement according to FIG. 1 during the initialphase of actuation of one cylinder,

FIG. 3 shows the previously illustrated arrangement during the expulsionof working fluid,

FIG. 4 shows the previously illustrated arrangement when one supplycylinder is empty and another supply cylinder is being actuated,

FIG. 5 is a perspective drawing of part of the arrangement according toFIGS. 1-4,

FIG. 6 is a perspective drawing of part of another embodiment of theinvention,

FIG. 7 is an exploded drawing of part of the arrangement according toFIG. 6, and

FIG. 8 is a schematic drawing of a control means for the arrangementaccording to FIGS. 1-5.

In the following description, the same reference numerals are used foridentical parts or parts with identical actions.

In the first embodiment of the invention, shown in FIGS. 1-5, anappliance housing 1 is provided that comprises an opening 2 on its frontside, into which a change-over magazine 40 can be inserted.

The change-over magazine contains a plurality of supply cylinders 10-1to 10-n; in the embodiment shown here, there are 8 such supply cylinders10. It is evident in the drawings that in this case the supply cylinders10 have been constructed directly within the change-over magazine or areformed by the magazine itself, and have not been inserted as separatecylinders.

Each of the supply cylinders 10 comprises a piston 12 that closes thecylinder at one end. In the interior of the supply cylinders 10 aworking fluid, in particular Ringer solution, is enclosed in a leakproofmanner.

Each supply cylinder communicates with an outlet 13 having a collectionchannel 45, which in turn is connected to a pressure conduit 20.

The pistons 12 comprise—as shown in the enlarged section of FIG. 4—aback-flow barrier 14 that keeps the piston 12 in its final position,i.e. when all the fluid has been expelled, as is known per se forsingle-use syringes.

After being inserted into the opening 2 of the housing 1, thechange-over magazine 40 is locked to a holder 41, so that it is firmlyretained within the appliance housing 1.

Within the housing 1 there are additionally provided actuation devices30-1 to 30-n, which are shown here as hydraulic cylinders but can ofcourse also be designed as electrically driven recirculating ball screwsor the like.

Each of the actuation devices 30 comprises a plunger 31, which isdisposed in the housing 1 in such a way that when the change-overmagazine 40 is in position, the actuating plungers 31 are situatedopposite the pistons 12 that face them.

The insertion position, i.e. the position of the components immediatelyafter the change-over magazine 40 has been inserted into the housing 1,is shown in FIG. 1. In this position the collection channel 5 and thepressure conduit 20 are still empty.

Now when the first actuation device 30-1 is actuated, so that itsplunger 31 is driven forward, the plunger—as shown in FIG. 3—presses thepiston 12 into the supply cylinder 10, so that fluid 11 passes throughan outlet 13 of the first supply cylinder 10-1 into the collectionchannel 45 and through the latter into the pressure conduit 20, whichconducts it to the working instrument (not shown).

As soon as the first supply cylinder 10-1 is empty (see FIG. 4), anothersupply cylinder 10-n is “triggered” to deliver its stored working fluid11 by way of the plunger 31 of the associated actuation device 30-n. Asthis occurs, the piston 12 of the emptied supply cylinder 10-1 isretained in its final position by the back-flow barrier 14, so that anyforce exerted by fluid emerging from the supply cylinder 10-n andpresent in the collection channel 45 cannot cause this piston 12 to bepushed backward.

The embodiment shown in FIGS. 6 and 7 differs from that according toFIGS. 1-5 in particular in that the change-over magazine 40 compriseschambers 42 into which individual supply cylinders 10 can be inserted asseparate “structural components”. In this arrangement the change-overmagazine 40 can be rotated about its axis, allowing supply cylinders10-1 to 10-n to be consecutively positioned so that their outlet 13 isconnected to a sealing device 43, which mediates a leakproof connectionbetween the associated supply cylinder 10 and the pressure conduit 20.These drawings show an opening needle 44, which is provided to openclosure devices (not shown) on the outlets 13 of the supply cylinders10; this needle opens the closure device of the relevant supply cylinder10 whenever the sealing device 43 is pressed against the outlet 13 ofthe supply cylinder 10. Exchanging of the supply cylinders 10 byrotation of the change-over magazine 40 thus corresponds somewhat to thereplacement of cartridges in (or at the entrance to) the barrel of arevolver.

FIG. 8 shows a—highly schematic—control means for the applianceaccording to FIGS. 1-5.

This control means comprises a computer 25 that is in controllingcommunication with the actuation devices 30-1 to 30-n. The plungers 31of the actuation devices 30-1 to 30-n, which in the present case areconstructed as electromotor drives (e.g., with recirculating ballscrews), exert pressure on the pistons 12 of the supply cylinders 10.The force thus employed can in this embodiment be controlled by thecurrent with which the electromotors M₁-M_(n) are driven by the computer25.

The outlets of the supply cylinders 10 are connected to the collectionchannel 45. Between the various supply cylinders 10 and the collectionchannel 45 are provided back-flow barriers 14, here constructed asback-flow valves, disposed in such a way that the pressure in thecollection channel 45 can in no case have an effect on a piston 12 thatat the moment is not being actuated with the corresponding force.

Between the collection channel 45 and the pressure conduit 20 leading toa working instrument 5, a ventilation device 46 is provided.

In addition path sensors 32 are provided, which send a signal to thecomputer 25 at least when the associated plunger 31 has reached itsfinal position.

With the arrangement shown in FIG. 8 it is now possible to drive theactuation devices 30-1 to 30-n in such a way that the supply cylinderscan be emptied one after another, and even in such a way that theiremptying periods overlap, so that the operator is not disturbed byfluctuations in pressure of the working fluid.

From the above it will be evident that a combination of the individualcharacteristics explained here is readily possible. For example, themagazine shown in FIGS. 6 and 7 can also be replaced by one according toFIG. 5 (to be used only once). Control by the computer 25 shown here canof course be replaced by provision of a corresponding cam-diskmechanism.

LIST OF REFERENCE NUMERALS

1 Appliance housing

2 Opening

5 Working instrument

10 Supply cylinder

11 Fluid

12 Piston

13 Outlet

14 Back-flow barrier

20 Pressure conduit

25 Computer

30 Actuation device

31 Plunger

32 Path sensor

40 Change-over magazine

41 Holder

42 Chamber

43 Sealing device

44 Opening needle

45 Collection channel

46 Ventilation device

50 Change-over device

1. Appliance for water-jet surgery, comprising a plurality of supplycylinders and pistons arrangements each defining an outlet and adaptedto store a working fluid that can be expelled, by means of the piston,through said outlet; a pressure conduit in communication with saidoutlets and into which said working fluid is expelled; at least oneactuation device to actuate the pistons; and a change-over device toshift the actuation from the piston of one supply cylinder to the pistonof another supply cylinder in order that, in use, the working fluid canbe ejected into the pressure conduit from consecutively emptying supplycylinders.
 2. Appliance according to claim 1, wherein said change-overdevice is adapted such that consecutive actuation periods of each of thepistons overlap one another in order that expulsion of the fluid intosaid pressure conduit is uninterrupted.
 3. Appliance according to claim1, wherein a sealing device is provided to provide a leak proofconnection to each fluid outlet.
 4. Appliance according to claim 1,wherein a plurality of actuation devices is provided.
 5. Applianceaccording to claim 1, wherein each of said pistons comprises a back-flowbarrier such that, after said piston has reached a position in which ithas expelled said working fluid from its associated cylinder, saidpiston cannot be pushed back into a previous position.
 6. Applianceaccording to claim 1, wherein an irreversibly openable transport gasketis provided at said outlet of each cylinder.
 7. Appliance according toclaim 1, wherein a change-over magazine is provided to receive a groupof supply cylinder and piston arrangements.
 8. Appliance according toclaim 7, wherein said change-over magazine defines chambers that closelysurround said the supply cylinders.
 9. Appliance according to claim 7,wherein collection devices are provided in the change-over magazine toconduct working fluid from said supply cylinders to said pressureconduit.
 10. Appliance according to claim 1, wherein ventilation devicesare provided for the removal of air from conduit sections locatedbetween the outlets of the supply cylinders and the pressure conduit.11. Appliance according to claim 10, wherein ventilation devices aredisposed in a change-over magazine.
 12. Appliance according to claim 7,wherein said change-over magazine is irreversibly connected to thepressure conduit to form a single-use unit.